Effects of Ramipril on the ventricular remodeling and GLUT4 in diabetic rats complicated with myocardial infarction

Objective To investigate ventricular remodeling and glucose transporter 4(GLUT4) expression in rat with type 2 diabetes mellitus(DM) complicated with myocardial infarction (MI), as well as the effects of ramipril on ventricular remodeling and CLUT4 expression. Method Diabetic animal model (DM) was produced by cholesterol-diet and intraperitoneal injedtion of streptozotocin (STZ,30 mg/kg). The successful model was identified based on the blood gulcose value > 6.7 mmol/L. Left anterior descending coronary artery was ligated to produce the model of MI. 46 wistar rats were randomly(random number) divided into 5 groups: DM + MI + placebo group(placebo group, n = 9), DM + MI + ramipril group(ramipril group, n = 10), DM + sham-operation group (DM group, n = 10),non-DM group + MI (MI group, n = 9), and non-DM + sham-operation group (n = 8). After six weeks, echocardiographic studies was performed ; Left ventricular mass index (LVMI), myocardial infarct size and myocardial collagen volume fraction(CVF) of non-infarction area were also detected. GLUT4 mRNA in the myocardium away from infarction region was measured with real-time fluorescent quantitative RT-PCR and the expression of GLUT4 protein was measured with western blot. Analysis of variance was used to compare the groups. P -values< 0.05 were considered to indicate statistically significant differences. Results Compared with Ml group and DM group,EF[(32 ±3)% vs. (65 ±4)%, P <0.01 and (32 ±3)% vs. (38 ±4)%, P <0.05 respectively] significantly decreased,while E/A ratio (P < 0.01), LVMI (P < 0.05) and CVF (P < 0.05) obviously increased in placebo group. The expression of GLUT4 mRNA and protein were similar between placebo group and DM group, however, much lower than those in MI group(P<0.01).In rampiril group, E/A ratio (P < 0.01), LVMI(3.1±0.2 vs.4.2±0.4, P <0.01) and CVF(P < 0.05) significantly decreased compared with placebo group, while EF[(45±3)% vs.(32±3)%, P <0.01] and the expression of GLUT4 mRNA and protein (P < 0.05) increased. Conclusions Rampiril could improve left ventricular hypertrophy and systolic/di-astolic dysfunction, increase the expression of GLUT4 mRNA and protein in diabetic rats complicated with MI. Key words: Rats;  Myocardial infarction;  Type 2 diabetes mellitus;  Ramipril;  Ventricular remodeling;  Color Doppler;  Cardiac function;  GLUT4